1. Field of the Invention
The present invention relates to a pneumatic tire decreased in rolling resistance while maintaining braking performance on wet road.
2. Description of the Related Art
In recent years, a pneumatic tire with low rolling resistance is requested by customers in order to improve fuel efficiency of passenger cars. Basically, energy loss generated in a tire tread portion accounts for about 50% of the rolling resistance of the tire. Therefore, in order to decrease the rolling resistance of the tire by preventing a large deformation of the tread portion, it is proposed to reduce the volume of crown and shoulder main grooves provided on the tread portion so as to improve the compression resistance thereof.
However, the tire is liable to deteriorate a drainage performance, such as braking performance on wet road due to crown and shoulder main grooves having low volume.